1. Field of the Invention
This invention relates generally to press apparatuses and, more particularly, to those of the type including a lower, stationary die having a convex top surface and an upper die arranged above the lower die for vertical movement relative thereto and having a concave bottom surface facing opposite to and conforming to the convex top surface of the lower die.
2. Description of the Prior Art
In use of this type of press apparatus, when a blank is fed on to the convex surface of the lower die, it is necessary to hold the blank in a horizontal position in order to prevent its dislocation and to enhance its moldability, thereby ensuring good appearance to the product obtained.
In prior art practice, it has been usual to hold the blank horizontal by placing it on an upwardly spring-biased pusher pin whose top end lies at the same level as the crest of the convex top surface of the lower die. Such pusher pin is contracted against the spring bias as the blank is pressed down to form but is again extended under the spring bias as the upper die starts to rise after the blank has been formed. The product formed, therefore, is tilted, being lifted on one side thereof by the pusher pin, and the angle of tilt of the product tends to vary piece by piece. This forms a practical disadvantage that any stable and efficient work-discharging operation can hardly be obtained even with an automatic discharger employed therefor in connection with the press apparatus.